Afghan President Ashraf Ghani says the Islamic State group has claimed responsibility for a suicide bombing Saturday that killed at least 33 people in eastern Afghanistan.

Officials say more than 100 other people were wounded in the attack in Jalalabad. President Ghani called the incident "horrific," as he announced Islamic State militants had taken credit. He referred to the group as "Daesh" — an acronym for its name in Arabic.

The Taliban had earlier denied responsibility for the bombing, calling it an "evil act."

Afghan security force members inspect the site of a suicide attack in Jalalabad, April 18, 2015.

The attacker set off the blast outside a bank where government employees were gathered to collect their salaries.

"I had received my salary, I was not in the line, then a motorbike came in, and I think a man in a suit went into the crowd and detonated his explosives," said Shir Aqha, an Afghan army officer who witnessed the bombing. "I heard two explosions, I can't remember what happened after that."

Others at the scene confirmed there were two blasts.

"My name is Njibullah, I'm a resident of Jalalabad. I just came in from Kabul, got out of the car when an explosion took place and that was followed by another blast," said another eye witness. "When I got here I saw many dead and wounded people and I offered help, all I could do for my countrymen."

The U.N. Assistance Mission in Afghanistan condemned the attack. In a statement, UNAMA said the continuing use of suicide attacks in densely populated areas may amount to a war crime. The statement called for immediate accountability for those responsible.